Earth Potential Electrodes in Permafrost and Tundra

Introduction : During the past two years, the authors installed a number of electrodes in the permafrost and tundra area of Point Barrow to obtain earth potential data. As ground temperatures decreased during the winter, the resistances of the first set of electrodes increased by several orders of magnitude and thus became useless. A second set of electrodes, with sodium chloride incorporated in the fill, proved entirely adequate for recording earth potentials. The installations and procedure for determining electrode resistances are described herein. Electrode resistance data versus time and ground temperatures are also presented.Ye

Effect of calcium on phenothiazine inhibition of neutrophil degranulation

The phenothiazines are known to be potent inhibitors of calmodulin and have been used as probes for examining calmodulin‐dependent cellular functions. We report here that the characteristics of phenothiazine inhibition of exocytosis in neutrophils more closely resemble their interaction with the annexins in vitro. Ca2+‐ dependent aggregation of liposomes mediated by either annexin I or annexin II was inhibited by the phenothiazines. Inhibition of liposome aggregation was not caused by interference with the binding of annexins to phospholipids. Rather, the phenothiazines increased the concentration of Ca2+ required for aggregation. Likewise, in neutrophils pepneabilized with streptolysin O, inhibition of degranulation by phenothiazines could be overcome by increasing [Ca2+]. These results suggest that inhibition by phenothiazines of neutrophil degranulation is secondary to the ability of these compounds to inhibit membrane‐membrane contact promoted by the annexins. J. Leukoc. Biol. 58: 114–118; 1995.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141375/1/jlb0114.pd

Hadal community structure: Implications from the Aleutian Trench

A 0.25-m2 box core from the Aleutian Trench (50°58.0\u27N, 171°37.5\u27W) was used to generate hypotheses concerning the regulation of benthic community structure in oceanic trenches. High food supply and the concentrating effects of trench topography are suggested by the unexpectedly high standing crop (1272 individuals of macrofaunal taxa m2) and by the feeding modes of the captured polychaetes...

Beam Line Design for the CERN Hiradmat Test Facility

The LHC phase II collimation project requires beam shock and impact tests of materials used for beam intercepting devices. Similar tests are also of great interest for other accelerator components such as beam entrance/exit windows and protection devices. For this purpose a dedicated High Radiation Material test facility (HiRadMat) is under study. This facility may be installed at CERN at the location of a former beam line. This paper describes the associated beam line which is foreseen to deliver a 450 GeV proton beam from the SPS with an intensity of up to 3×10**13 protons per shot. Different beam line designs will be compared and the choice of the beam steering and diagnostic elements will be discussed, as well as operational issues

Comparison of subjective and objective evaluation of screen-film systems for chest radiography

A subjective and an objective comparison of six screen-film systems is reported. Among the objective parameters which characterise image quality, resolution appeared to be the most critical one when compared with the averaged ranking produced by the radiologists. The results have shown that a relationship between dose and image quality can be established for most of screen-film systems tested. The problem which remains in the optimisation procedure of chest imaging, is the definition of the level of image quality requirements

European Survey of Image Quality Assessment Methods Used in Mammography

The definition of reference dose levels has to be linked with the definition of image quality. Unfortunately, there is still no general agreement on the definition of image quality in mammography, and most of the protocols used are based on the detectability of objects having various shapes and contrasts. To facilitate the task of assessing image quality, scoring methods are often used to produce a single number representative of the imaging chain performance. The goal of this study is to present a comparison between different ways of assessing image quality commonly used in Europe. A set of five mammograms, having different image quality levels, has been obtained with several test objects and compared. The results show large sensitivity variations among the different methods. Concerted work between radiologists and physicists is still required to define the radiological tasks and develop objective ways to measure image quality in mammography

Initial-state dependence in time-dependent density functional theory

Time-dependent density functionals in principle depend on the initial state of the system, but this is ignored in functional approximations presently in use. For one electron it is shown there is no initial-state dependence: for any density, only one initial state produces a well-behaved potential. For two non-interacting electrons with the same spin in one-dimension, an initial potential that makes an alternative initial wavefunction evolve with the same density and current as a ground state is calculated. This potential is well-behaved and can be made arbitrarily different from the original potential

Reduction of nickel oxide particles by hydrogen studied in an environmental TEM

In situ reduction of nickel oxide (NiO) particles is performed under 1.3mbar of hydrogen gas (H2) in an environmental transmission electron microscope (ETEM). Images, diffraction patterns and electron energy-loss spectra (EELS) are acquired to monitor the structural and chemical evolution of the system during reduction, whilst increasing the temperature. Ni nucleation on NiO is either observed to be epitaxial or to involve the formation of randomly oriented grains. The growth of Ni crystallites and the movement of interfaces result in the formation of pores within the NiO grains to accommodate the volume shrinkage associated with the reduction. Densification is then observed when the sample is nearly fully reduced. The reaction kinetics is obtained using EELS by monitoring changes in the shapes of the Ni L2,3 white lines. The activation energy for NiO reduction is calculated from the EELS data using both a physical model-fitting technique and a model-independent method. The results of the model-fitting procedure suggest that the reaction is described by Avrami models (whereby the growth and impingement of Ni domains control the reaction), in agreement with the ETEM observation